Pyridinesulfonamide derivatives and herbicides

ABSTRACT

A pyridinesulfonamide derivative of the formula (I) and a salt thereof: ##STR1## wherein R 1  is a halogen atom, a trifluoromethyl group, a C 1  -C 6  alkoxycarbonyl group, a C 1  -C 6  mono- or di-alkylaminocarbonyl group, a C 1  -C 6  alkxoy group, a C 1  -C 6  alkylsulfonyl group, a C 1  -C 6  alkylthio group, a C 1  -C 6  alkyl group substituted by a C 1  -C 6  alkoxy group, a C 1  -C 6  alkyl group substituted by a C 1  -C 6  mono- or poly-halogenoalkoxy group, a C 1  -C 6  mono- or poly-halogenoalkoxy group, a C 1  -C 6  mono- or di-alkylaminosulfonyl group, a C 1  -C 6  alkoxyaminosulfonyl group substituted by a C 1  -C 6  alkyl group, a nitro group, a C 1  -C 6  alkyl group substituted by a C 1  -C 6  alkylthio group, a C 1  -C 5  alkyl group substituted by a C 1  -C 6  alkylsulfonyl group, or a C 1  -C 6  alkyl group substituted by a C 1  -C 6  alkoxycarbonyl group; 
     R 2  is a hydrogen atom or a halogen atom; 
     X is a oxygen atom or a sulfur atoms; and ##STR2## which are useful as herbicides.

The present invention relates to novel pyridinesulfonamide derivatives and salts thereof, and herbicides containing such compounds as active ingredients.

It is indispensable to use herbicides to protect important crop plants such as rice, wheat, corn, soybean, cotton and sugar beet from weeds and thereby to increase the harvest. Especially in recent years, a selective herbicide is desired which is capable of selectively killing weeds without showing any phytotoxicity against crop plants when applied to the foliages of crop plants and weeds simultaneously in a field where such useful crop plants and weeds are coexistent. Further, with a view to avoiding environmental pollution and reducing the costs for transportation and application, researches and developments have been conducted for many years for compounds having high herbicidal effects at low doses. Some of the compounds having such properties are presently used as selective herbicides. However, there still exists a need for new compounds having such properties.

As the prior art showing a chemical structure similar to that of the compounds of the present invention, Japanese Unexamined Patent Publication No. 267576/1986 discloses pyridinesulfonylurea compounds, and Japanese Unexamined Patent Publication No. 122671/1988 discloses sufonamide compounds having a pyrazoline structure.

In Japanese Unexamined Patent Publication No. 122671/1988, heteroarylsulfonamide compounds are generally and broadly claimed on the basis of the disclosure of pyrazolesulfonamide derivatives and thiophenesulfonamide derivatives in addition to substituted benzene sulfonamide derivatives and substituted benzylsulfonamide derivatives, as sulfonamide compounds having a pyrazoline structure. However, in this publication, the compounds of the present invention are not specifically disclosed, and no specific description is given also as to the herbicidal activities of pyrazolesulfonamide derivatives although the usefulness of the heteroarylsulfonamide compounds are generally described.

Pyridinesulfonamide derivatives having a pyrazoline structure, like the compounds of the present invention, have not been known at all, and they are novel compounds.

The present inventors have conducted extensive researches over years to develop selective herbicides for important crop plants and have studied herbicidal properties of many compounds with an aim to find out compounds having higher herbicidal activities as well as selectivity. As a result, it has been found that pyridinesulfonamide derivatives of the following formula (I) and agriculturally suitable salts thereof (hereinafter referred to as the compounds of the present invention) exhibit remarkably strong herbicidal activities against many weeds in soil treatment or in foliage treatment and at the same time have a high level of safety for important crop plants such as wheat, corn, cotton, soybean, sugar beet and rice. The present invention has been accomplished on the basis of this discovery. On the other hand, since the compounds of the present invention show high herbicidal activities at a very low dose as compared with conventional herbicides, they are also useful as herbicides for orchards or for non-agricultural fields.

Namely, the present invention provides a pyridinesulfonamide derivative of the formula (I) and a salt thereof: ##STR3## wherein R¹ is a halogen atom, a trifluoromethyl group, a C₁ -C₆ alkoxycarbonyl group, a C₁ -C₆ mono- or di-alkylaminocarbonyl group, a C₁ -C₆ alkoxy group alkylsulfonyl group, a C₁ -C₆ alkylthio group, a C₁ -C₆ alkyl group substituted by a C₁ -C₆ alkoxy group, a C₁ -C₆ alkyl group substituted by a C₁ -C₆ mono- or poly-halogenoalkoxy group, a C₁ -C₆ mono- or poly-halogenoalkoxy group, a C₁ -C₆ mono- or di-alkylaminosulfonyl group, a C₁ -C₆ alkoxyaminosulfonyl group substituted by a C₁ -C₆ alkyl group, a nitro group, a C₁ -C₆ alkyl group substituted by a C₁ -C₆ alkylthio group, a C₁ -C₆ alkyl group Substituted by a C₁ -C₆ alkylsulfonyl group, or a C₁ -C₆ alkyl group substituted by a C₁ -C₆ alkoxycarbonyl group;

R² is a hydrogen atom or a halogen atom;

X is a oxygen atom or a sulfur atom; and ##STR4## wherein each of a, b, c and d independently represents a hydrogen atom, a C₁ -C₆ alkyl group, a C₂ -C₆ alkenyl group, a C₂ -C₆ alkynyl group, a C₁ -C₆ alkyl group mono- or poly substituted by a halogen atom, a C₁ -group, a C₁ -C₆ alkyl group substituted by a C₁ -C₆ alkoxy group, a C₁ -C₆ alkoxycarbonyl group, a C₁ -C₆ alkyl group substituted by a C₁ -C₆ alkylthio group, a C₁ -C₆ alkyl group Substituted by a C₁ -C₆ alkylsulfonyl group, a C₁ -C₆ alkylthio group, a C₁ -C₆ alkylcarbonyl group, a C₃ -C₇ cycloalkyl group, a C₃ -C₇ cycloalkenyl group, a cyano group, a phenyl or benzyl group (provided that this phenyl or benzyl group may be mono- or poly-substituted by a halogen atom, a trifluoromethyl group, a C₁ -C₆ alkyl group, a C₁ -C₆ alkoxy group, a C₁ -C₆ alkoxycarbonyl group or a nitro group), a 5- or 6-membered heterocyclic group (provided that such a heterocyclic group contains from 1 to 3 hetero atoms selected from the group consisting of nitrogen atoms, oxygen atoms and sulfur atoms in the ring, or contains a sulfonyl group, and such a heterocyclic group may be mono- or poly-substituted by a C₁ -C₆ alkyl group, a C₁ -C₆ alkoxy group, a halogen atom, a trifluoromethyl group, a nitro group or a C₁ -C₆ alkoxycarbonyl group), a naphthyl group, a benzene-condensed heterocyclic group (provided that such a benzene-condensed heterocyclic group contains 1 or 2 hetero atoms selected from the group consisting of nitrogen atoms, oxygen atoms and sulfur atoms in the ring, and such a benzene-condensed heterocyclic group may mono- or poly-substituted by a C₁ -C₆ alkyl group, a C₁ -C₆ alkoxy group, a halogen atom, a trifluoromethyl group, a nitro group or a C₁ -C₆ alkoxycarbonyl group).

The present invention also provides a selective herbicide containing one or more compounds of the present invention as active ingredients.

Now, the present invention will be described in detail with reference to the preferred embodiments.

The compounds of the formula (I) of the present invention can easily be prepared by any one of the following reaction schemes 1 to 3. ##STR5## In the above formulas, R¹, R², G and X are as defined above.

Namely, a pyridinesulfonyliso(thio)cyanate derivative (II) is dissolved in a sufficiently dried inert solvent such as benzene, toluene, dichloromethane, dichloroethane, tetrahydrofuran, dioxane, acetonitrile, acetone or methyl ethyl ketone, then a pyrazoline derivative of the formula (III) is added thereto, and the mixture is stirred, whereby the reaction usually proceeds swiftly and the compound (I) cf the present invention is obtained. When the reaction hardly proceeds, a very small amount of a suitable base such as triethylamine, triethylenediamine, pyridine, 1,8-diazabicyclo[5,4,0]-7-undecene (DBU), a sodium alkoxide, sodium hydride or potassium carbonate may be added, whereby the reaction readily proceeds. ##STR6## In the above formulas, R¹, R², G and X are as defined above, and Y is a C₁ -C₆ alkyl group or a phenyl group.

Namely, a pyridinesulfonamide derivative (IV) is reacted with chloro(thio)formic acid ester or (thio)carbonic acid diester in a solvent such as acetone, methyl ethyl ketone, acetonitrile, tetrahydrofuran, dioxane, dichloromethane, dichloroethane, N,N-dimethylformamide, benzene or toluene in the presence of a base such as pyridine, triethylamine, 1,8-diazabicyclo[5,4,0]-7-undecene (DBU), potassium carbonate, a sodium alkoxide, sodium hydride, sodium hydroxide or potassium hydroxide to obtain a compound (V). Then, it is heated together with a compound (III) in a solvent such as tetrahydrofuran, dioxane, benzene, toluene, acetone, methyl ethyl ketone, dichloromethane, dichloroethane or N,N-dimethylformamide in the presence of a base such as pyridine, triethylamine, DBU, potassium carbonate, a sodium alkoxide, sodium hydride, sodium hydroxide or potassium hydroxide to obtain the compound (I) of the present invention. ##STR7## In the above formulas, R¹, R², G and Y are as defined above.

Namely, a pyridinesulfonamide derivative (IV) is reacted with a carbamate derivative (VI) in a solvent such as acetone, methyl ethyl ketone, acetonitrile, tetrahydrofuran, dioxane, dichloromethane, dichloroethane, N,N-dimethylformamide, benzene or toluene in the presence of an inorganic base such as potassium carbonate, sodium hydroxide or potassium hydroxide, or an organic base such as triethylamine, pyridine or DBU, to obtain the compound of the present invention (I; X=0).

The pyridinesulfonyliso(thio)cyanate derivative (II) to be used as a starting material in reaction scheme 1 can be synthesized from a pyridinesulfonamide derivative (IV) in accordance with the methods disclosed in e.g. Japanese Unexamined Patent Publications No. 148879/1983, No. 31775/1984 and No. 13266/1980.

The pyridinesulfonamide derivative (IV) to be used as a starting material in reaction schemes 2 and 3 can be synthesized in accordance with the methods disclosed in e.g. Japanese Unexamined Patent Publications No. 223180/1987 and No. 267576/1986.

The pyrazoline (III) to be used as a starting material for the above reactions, can readily be synthesized in accordance with e.g. Japanese Unexamined Patent Publication No. 122671/1988. Representative examples are shown as reaction schemes 4 and 5. ##STR8##

Now, the syntheses of the compounds of the present invention will be described in detail with reference to Reference Example and Preparation Example. However, it should be understood that the present invention is by no means restricted by such specific Examples.

REFERENCE EXAMPLE Preparation of methyl N-)3-trifluoromethylpyridine-2-sulfonyl)carbamate ##STR9##

Methyl chloroformate (3.31 g, 35 mmol) was added under cooling with ice to a dry acetonitrile (150 ml) solution containing 3-trifluoromethylpyridine-2-sulfonamide (7.91 g, 35 mmol) and triethylamine (16 ml), and the mixture was continuously stirred at room temperature for 3 hours. Then, the solvent was distilled off under reduced pressure, and the residue was dissolved in 300 ml of water. A small amount of insoluble substances were removed by filtration, and the filtrate was adjusted to pH of 1 to 2 with concentrated hydrochloric acid under cooling with ice. Precipitated crystals were collected by filtration and thoroughly washed with water, then washed with a solvent mixture of ethyl ether/n-hexane and dried to obtain 4.4 g of desired methyl N-(3-trifluoromethylpyridine-2-sulfonyl)carbamate. Melting point: 128°-129° C.

PREPARATION EXAMPLE 1 Preparation of 1-(3-trifluoromethylpyridine-2-sulfonylcarbamoyl)-3-methyl-5-phenyl-2-pyrazoline ##STR10##

A dry dioxane (10 ml) solution containing methyl N-(3-trifluoromethylpyridine-2-sulfonyl)carbamate (0.43 g, 1.5 mmol), 3-methyl-5-phenyl-2-pyrazoline (0.48 g, 3.0 mmol) and pyridine (0.45 g) gas refluxed under heating and stirring for one hour. After cooling the mixture, the solvent was distilled off under reduced pressure, and the residue was stirred together with ethyl ether. Precipitated crystals were collected by filtration and then thoroughly washed with ethyl ether, and the crystals were suspended in 20 ml of water. Then, the pH was adjusted to a level of from 1 to 2 with concentrated hydrochloric acid, and the suspension was stirred at room temperature for 5 minutes. Crystals were collected by filtration, thoroughly washed with water and then with ethyl ether and dried to obtain 0.51 g of desired 1-(3-trifluoromethylpyridine-2-sulfonylcarbamoyl)-3-methyl-5-phenyl-2-pyrazoline. Melting point: 185°-187° C.

PREPARATION EXAMPLE 2 Preparation of 1-(3-trifluoromethylpyridine-2-sulfonylcarbamoyl)-3,5-dimethyl-5-phenyl-2-pyrazoline ##STR11##

A dry dioxane (10 ml) solution containing methyl N-(3-trifluoromethylpyridine-2-sulfonyl)carbamate (0.43 g, 1.5 mmol), 3,5-dimethyl-5-phenyl-2-pyrazoline (0.52 g, 3.0 mmol) and pyridine (0.45 g) was refluxed under heating and stirring for one hour. After cooling the mixture, the solvent was distilled off under reduced pressure, and the residue was stirred together with ethyl ether. Precipitated crystals were collected by filtration and then thoroughly washed with ethyl ether, and the crystals were suspended in 20 ml of water. Then, the pH was adjusted to a level of from 1 to 2 with concentrated hydrochloric acid, and the suspension was stirred at room temperature for 5 minutes. Crystals were collected by filtration, thoroughly washed with water and then with ethyl ether and dried to obtain 0.55 g of desired 1-(3-trifluoromethylpyridine-2-sulfonylcarbamoyl)-3,5-dimethyl-5-phenyl-2-pyrazoline. Melting point: 152°-153° C.

The structures and the physical values or properties of the compounds prepared in the same manner as the above Preparation Example are shown below.

    ______________________________________                                          ##STR12##                                                                     Compound No. 1      m.p. 185-187° C.                                     ##STR13##                                                                     Compound No. 2      m.p. 183˜184° C.                               ##STR14##                                                                     Compound No. 3      m.p. 152˜153° C.                               ##STR15##                                                                     Compound No. 4      m.p. 160˜161° C.                               ##STR16##                                                                     Compound No. 5      m.p. 177˜178° C.                               ##STR17##                                                                     Compound No. 6      m.p. 144˜145° C.                               ##STR18##                                                                     Compound No. 7      m.p. 138˜140° C.                               ##STR19##                                                                     Compound No. 8      m.p. 185˜186° C.                               ##STR20##                                                                     Compound No. 9      m.p. 195˜196° C.                               ##STR21##                                                                     Compound No. 10     m.p. 157˜158° C.                               ##STR22##                                                                     Compound No. 11     m.p. 150˜151° C.                               ##STR23##                                                                     Compound No. 12     m.p. 129˜130° C.                               ##STR24##                                                                     Compound No. 13     m.p. 178˜179° C.                               ##STR25##                                                                     Compound No. 14     Oil                                                         ##STR26##                                                                     Compound No. 15     m.p. 149˜150° C.                               ##STR27##                                                                     Compound No. 16     m.p. 207˜208° C.                               ##STR28##                                                                     Compound No. 17     Glassy                                                      ##STR29##                                                                     Compound No. 18     m.p. 168˜170° C.                               ##STR30##                                                                     Compound No. 19     m.p. 168˜169° C.                               ##STR31##                                                                     Compound No. 20     m.p. 116˜117° C.                               ##STR32##                                                                     Compound No. 21     m.p. 178.5˜179.5° C.                           ##STR33##                                                                     Compound No. 22     m.p. 136˜137° C.                               ##STR34##                                                                     Compound No. 23     m.p. 177˜178° C.                               ##STR35##                                                                     Compound No. 24     m.p. 186˜187° C.                               ##STR36##                                                                     Compound No. 25     m.p. 188˜189° C.                               ##STR37##                                                                     Compound No. 26     m.p. 106˜107° C.                               ##STR38##                                                                     Compound No. 27     m.p. 136˜137° C.                               ##STR39##                                                                     Compound No. 28     m.p. 124˜125° C.                               ##STR40##                                                                     Compound No. 29     m.p. 160˜161° C.                               ##STR41##                                                                     Compound No. 30     m.p. 113˜114° C.                               ##STR42##                                                                     Compound No. 31     m.p. 177˜178° C.                               ##STR43##                                                                     Compound No. 32     m.p. 187˜188° C.                              ______________________________________                                    

Now, Table 1 presents examples of specific compounds of the present invention including the compounds prepared in the preceding Examples. However, it should be understood that the compounds of the present invention are not limited to such specific examples.

In Table 1, Gn in the structural formula has the same meaning as G and includes all of G1 to G479 as defined hereinafter, and the symbols used in the Table have the following meanings: Me: methyl group, Et: ethyl group, Pr-n: n-propyl group, Pr-i: isopropyl group, Bu-n: n-butyl group, Pen-n: n-pentyl group and Ph: phenyl group.

                  TABLE 1                                                          ______________________________________                                          ##STR44##                                                                     R.sup.1            R.sup.2    X                                                ______________________________________                                         Cl                 H          O                                                Cl                 H          S                                                Cl                 F          O                                                Cl                 F          S                                                Cl                 Cl         O                                                Cl                 Cl         S                                                Br                 H          O                                                Br                 H          S                                                Br                 F          O                                                Br                 F          S                                                Br                 Cl         O                                                Br                 Cl         S                                                CF.sub.3           H          O                                                CF.sub.3           H          S                                                CF.sub.3           F          O                                                CF.sub.3           F          S                                                CF.sub.3           Cl         O                                                CF.sub.3           Cl         S                                                CO.sub.2 Me        H          O                                                CO.sub.2 Me        H          S                                                CO.sub.2 Me        F          O                                                CO.sub.2 Me        F          S                                                CO.sub.2 Me        Cl         O                                                CO.sub.2 Me        Cl         S                                                CO.sub.2 Et        H          O                                                CO.sub.2 Et        H          S                                                CO.sub.2 Et        F          O                                                CO.sub.2 Et        F          S                                                CO.sub.2 Et        Cl         O                                                CO.sub.2 Et        Cl         S                                                CO.sub.2 Pr-n      H          O                                                CO.sub.2 Pr-n      H          S                                                CO.sub.2 Pr-n      F          O                                                CO.sub.2 Pr-n      F          S                                                CO.sub.2 Pr-n      Cl         O                                                CO.sub.2 Pr-n      Cl         S                                                CONMe.sub.2        H          O                                                CONMe.sub.2        H          S                                                CONMe.sub.2        F          O                                                CONMe.sub.2        F          S                                                CONMe.sub.2        Cl         O                                                CONMe.sub.2        Cl         S                                                OMe                H          O                                                OMe                H          S                                                OMe                F          O                                                OMe                F          S                                                OMe                Cl         O                                                OMe                Cl         S                                                OEt                H          O                                                OEt                H          S                                                OEt                F          O                                                OEt                F          S                                                OEt                Cl         O                                                OEt                Cl         S                                                SO.sub.2 Me        H          O                                                SO.sub.2 Me        H          S                                                SO.sub.2 Me        F          O                                                SO.sub.2 Me        F          S                                                SO.sub.2 Me        Cl         O                                                SO.sub.2 Me        Cl         S                                                SO.sub.2 Et        H          O                                                SO.sub.2 Et        H          S                                                SO.sub.2 Et        F          O                                                SO.sub.2 Et        F          S                                                SO.sub.2 Et        Cl         O                                                SO.sub.2 Et        Cl         S                                                SMe                H          O                                                SMe                H          S                                                SMe                F          O                                                SMe                F          S                                                SMe                Cl         O                                                SMe                Cl         S                                                CH.sub.2 OMe       H          O                                                CH.sub.2 OMe       H          S                                                CH.sub.2 OMe       F          O                                                CH.sub.2 OMe       F          S                                                CH.sub.2 OMe       Cl         O                                                CH.sub.2 OMe       Cl         S                                                CH.sub.2 OEt       H          O                                                CH.sub.2 OEt       H          S                                                CH.sub.2 OEt       F          O                                                CH.sub.2 OEt       F          S                                                CH.sub.2 OEt       Cl         O                                                CH.sub.2 OEt       Cl         S                                                CH.sub.2 OCHF.sub.2                                                                               H          O                                                CH.sub.2 OCHF.sub.2                                                                               H          S                                                CH.sub.2 OCHF.sub.2                                                                               F          O                                                CH.sub.2 OCHF.sub.2                                                                               F          S                                                CH.sub.2 OCHF.sub.2                                                                               Cl         O                                                CH.sub.2 OCHF.sub.2                                                                               Cl         S                                                CH.sub.2 OCH.sub.2 CF.sub.3                                                                       H          O                                                CH.sub.2 OCH.sub.2 CF.sub.3                                                                       H          S                                                CH.sub.2 OCH.sub.2 CF.sub.3                                                                       F          O                                                CH.sub.2 OCH.sub.2 CF.sub.3                                                                       F          S                                                CH.sub.2 OCH.sub.2 CF.sub.3                                                                       Cl         O                                                CH.sub.2 OCH.sub.2 CF.sub.3                                                                       Cl         S                                                OCH.sub.2 CH.sub.2 Cl                                                                             H          O                                                OCH.sub.2 CH.sub.2 Cl                                                                             H          S                                                OCH.sub.2 CH.sub.2 Cl                                                                             F          O                                                OCH.sub.2 CH.sub.2 Cl                                                                             F          S                                                OCH.sub.2 CH.sub.2 Cl                                                                             Cl         O                                                OCH.sub.2 CH.sub.2 Cl                                                                             Cl         S                                                SO.sub.2 NMe.sub.2 H          O                                                SO.sub.2 NMe.sub.2 H          S                                                SO.sub.2 NMe.sub.2 F          O                                                SO.sub.2 NMe.sub.2 F          S                                                SO.sub.2 NMe.sub.2 Cl         O                                                SO.sub.2 NMe.sub.2 Cl         S                                                SO.sub.2 N(OMe)Me  H          O                                                SO.sub.2 N(OMe)Me  H          S                                                SO.sub.2 N(OMe)Me  F          O                                                SO.sub.2 N(OMe)Me  F          S                                                SO.sub.2 N(OMe)Me  Cl         O                                                SO.sub.2 N(OMe)Me  Cl         S                                                NO.sub.2           H          O                                                NO.sub.2           H          S                                                NO.sub.2           F          O                                                NO.sub. 2          F          S                                                NO.sub.2           Cl         O                                                NO.sub.2           Cl         S                                                CH.sub.2 SMe       H          O                                                CH.sub.2 SMe       H          S                                                CH.sub.2 SMe       F          O                                                CH.sub.2 SMe       F          S                                                CH.sub.2 SMe       Cl         O                                                CH.sub.2 SMe       Cl         S                                                CH.sub.2 SEt       H          O                                                CH.sub.2 SEt       H          S                                                CH.sub.2 SEt       F          O                                                CH.sub.2 SEt       F          S                                                CH.sub.2 SEt       Cl         O                                                CH.sub.2 SEt       Cl         S                                                CH.sub.2 SO.sub.2 Me                                                                              H          O                                                CH.sub.2 SO.sub.2 Me                                                                              H          S                                                CH.sub.2 SO.sub.2 Me                                                                              F          O                                                CH.sub.2 SO.sub.2 Me                                                                              F          S                                                CH.sub.2 SO.sub.2 Me                                                                              Cl         O                                                CH.sub.2 SO.sub.2 Me                                                                              Cl         S                                                CH.sub.2 SO.sub.2 Et                                                                              H          O                                                CH.sub.2 SO.sub.2 Et                                                                              H          S                                                CH.sub.2 SO.sub.2 Et                                                                              F          O                                                CH.sub.2 SO.sub.2 Et                                                                              F          S                                                CH.sub.2 SO.sub.2 Et                                                                              Cl         O                                                CH.sub.2 SO.sub.2 Et                                                                              Cl         S                                                CH.sub.2 CO.sub.2 Me                                                                              H          O                                                CH.sub.2 CO.sub.2 Me                                                                              H          S                                                CH.sub.2 CO.sub.2 Me                                                                              F          O                                                CH.sub.2 CO.sub.2 Me                                                                              F          S                                                CH.sub.2 CO.sub.2 Me                                                                              Cl         O                                                CH.sub.2 CO.sub.2 Me                                                                              Cl         S                                                CH.sub.2 CO.sub. 2 Et                                                                             H          O                                                CH.sub.2 CO.sub.2 Et                                                                              H          S                                                CH.sub.2 CO.sub.2 Et                                                                              F          O                                                CH.sub.2 CO.sub.2 Et                                                                              F          S                                                CH.sub.2 CO.sub.2 Et                                                                              Cl         O                                                CH.sub.2 CO.sub.2 Et                                                                              Cl         S                                                ______________________________________                                          ##STR45##

When the compound of the present invention is to be used as a herbicide, it is usually mixed with a suitable carrier, for instance, a solid carrier such as clay, talc, bentonite or diatomaceous earth, or a liquid carrier such as water, an alcohol (such as methanol or ethanol), an aromatic hydrocarbon (such as benzene, toluene or xylene), a chlorinated hydrocarbon, an ether, a ketone, an ester (such as ethyl acetate), or an acid amide (such as N,N-dimethylformamide). If desired, an emulsifier, a dispersing agent, a suspending agent, a penetrating agent, a spreader or a stabilizer may be added to prepare an optional formulation such as a liquid formulation, an emulsifiable concentrate, a wettable powder, a dust, a granule or a flowable.

Now, Formulation Examples of the herbicides containing the compounds of the present invention as active ingredients, will be given. However, it should be understood that the present invention is by no means restricted to such specific Examples. In the following Formulation Examples, "parts" means "parts by weight".

    ______________________________________                                         FORMULATION EXAMPLE 1: Wettable powder                                         ______________________________________                                         Compound No. 1 of the present invention                                                                 20 parts                                              Zeeklite A (tradename for a kaolin-type                                                                 76 parts                                              clay, manufactured by Zeeklite Industries,                                     Co., Ltd.)                                                                     Sorpol 5039 (tradename for a mixture of a                                                                2 parts                                              nonionic surfactant and an anionic                                             surfactant, manufactured by Toho Chemical                                      Industry Co., Ltd.)                                                            Carplex (tradename for a coagulation-                                                                    2 parts                                              preventing agent composed of a mixture of a                                    surfactant and fine silica powder,                                             manufactured by Shionogi Pharmaceutical                                        Co., Ltd.)                                                                     ______________________________________                                    

The above ingredients are homogeneously pulverized and mixed to form a wettable powder.

    ______________________________________                                         FORMULATION EXAMPLE 2: Wettable powder                                         ______________________________________                                         Compound No. 3 of the present invention                                                                 40 parts                                              Zeeklite A (tradename for a kaolin-type                                                                 54 parts                                              clay, manufactured by Zeeklite Industries,                                     Co., Ltd.)                                                                     Sorpol 5039 (tradename for a mixture of a                                                                2 parts                                              nonionic surfactant and an anionic                                             surfactant, manufactured by Toho Chemical                                      Industry Co., Ltd.)                                                            Carplex (tradename for a coagulation-                                                                    4 parts                                              preventing agent composed of a mixture of a                                    surfactant and fine silica powder,                                             manufactured by Shionogi Pharmaceutical                                        Co., Ltd.)                                                                     ______________________________________                                    

The above ingredients are homogeneously pulverized and mixed to form a wettable powder.

    ______________________________________                                         FORMULATION EXAMPLE 3: Emulsifiable concentrate                                ______________________________________                                         Compound No. 19 of the present invention                                                                 5 parts                                              Xylene                   75 parts                                              N,N-dimethylformamide    15 parts                                              Sorpol 2680 (tradename for a mixture of a                                                                5 parts                                              nonionic surfactant and an anionic                                             surfactant, manufactured by Toho Chemical                                      Industry Co., Ltd.)                                                            ______________________________________                                    

The above ingredients are homogeneously mixed to form an emulsifiable concentrate. In its use, the above emulsifiable concentrate is diluted with water from 10 to 10,000 times and applied so that the active ingredient will be from 0.0005 to 10 kg per hectare.

    ______________________________________                                         FORMULATION EXAMPLE 4: Flowable                                                ______________________________________                                         Compound No. 21 of the present invention                                                                 25     parts                                         Agrizole S-710 (tradename for a nonionic                                                                 10     parts                                         surfactant, manufactured by Kao Corp.)                                         Runox 1000C (tradename for an anionic                                                                    0.5    part                                          surfactant, manufactured by Toho Chemical                                      Industry Co., Ltd.)                                                            1% Rodopol water (tradename for a thickener,                                                             20     parts                                         manufactured by Rhone-Poulenc)                                                 Water                     44.5   parts                                         ______________________________________                                    

The above ingredients were homogeneously mixed to obtain a flowable.

    ______________________________________                                         FORMULATION EXAMPLE 5: Flowable                                                ______________________________________                                         Compound No. 3 of the present invention                                                                  40     parts                                         Agrizole S-710 (tradename for a nonionic                                                                 10     parts                                         surfactant, manufactured by Kao Corp.)                                         Runox 1000C (tradename for an anionic                                                                    0.5    part                                          surfactant, manufactured by Toho Chemical                                      Industry Co., Ltd.)                                                            1% Rodopol water (tradename for a thickener,                                                             20     parts                                         manufactured by Rhone-Poulenc)                                                 Water                     29.5   parts                                         ______________________________________                                    

The above ingredients were homogeneously mixed to obtain a flowable.

    ______________________________________                                         FORMULATION EXAMPLE 6: Granule                                                 ______________________________________                                         Compound No. 13 of the present invention                                                                 1      part                                          Bentonite                 55     parts                                         Talc                      44     parts                                         ______________________________________                                    

The above ingredients were homogeneously mixed and pulverized, and after an addition of a small amount of water, the mixture was stirred, mixed and granulated by an extrusion-type granulating machine, followed by drying to obtain a granule.

Further, the compound of the present invention may be combined with other herbicides, various insecticides, fungicides and synergism agents at the time of the preparation of the formulations or at the time of the application, as the case requires.

As such other herbicides, compound disclosed in Farm Chemicals Handbook (1989) may, for example, be mentioned.

The compound of the present invention can be applied to control various weeds not only in the agricultural and horticultural fields such as upland fields, paddy fields or orchards, but also in non-agricultural fields such as play grounds, non-used vacant fields or railway sides.

The dose varies depending upon the application site, the season for application, the manner of application, the type of weeds to be controlled, the type of crop plants, etc. However, the dose is usually within a range of from 0.005 to 10 kg per hectare as the amount of the active ingredient.

Now, the herbicidal activities of the compounds of the present invention will be described in detail with reference to the following Test Examples. The Compound Nos. referred to in the Test Examples correspond to the Compound Nos. given above.

TEST EXAMPLE 1 Test on the herbicidal effects in soil treatment

A plastic box having a length of 15 cm, a width of 22 cm and a depth of 6 cm was filled with a sterilized diluvial soil, and seeds of Echinochloa crus-galli, Digitaria edscendens, Cyperus microiria, Solanum nigrum, Galinsoga ciliata, Rorippa indica, Oryza sativa, Zea mays, Triticum aestivum, Glycine max and Gossypium herbaceum were sown, and the soil was covered thereon in the thickness of about 1.5 cm, and then a herbicide solution was applied onto the surface of the soil uniformly so that the active ingredient was distributed at a predetermined concentration. The herbicide solution was prepared by diluting the wettable powder as described in the foregoing Formulation Examples with water and applied onto the entire soil surface by means of a small spray. Four weeks after the application of the herbicidal solution, the herbicidal effects against each weed and the phytotoxicities against each crop plant were determined on the basis of the following standard ratings. The results are shown in Table 2. (Compound Nos. correspond to Compound Nos. in the Examples.) Some of the compounds of the present invention exhibit selectivity for certain crop plants.

Standard ratings:

5: Growth control rate of more than 90% (almost completely withered)

4: Growth control rate of from 70 to 90%

3: Growth control rate of from 40 to 70%

2: Growth control rate of from 20 to 40%

1: Growth control rate of from 5 to 20%

0: Growth control rate of less than 5% (almost non-effective)

The above growth control rates were calculated by the following equation: ##EQU1## where T: Weight of the weed grown above the soil surface of the treated area

N: Weight of the weed grown above the soil surface of the non-treated area

TEST EXAMPLE 2 Test on the herbicidal effects in foliage treatment

A plastic box having a length of 15 cm, a width of 22 cm and a depth of 6 cm was filled with a sterilized diluvial soil, and seeds of Echinochloa crus-galli, Digitaria adscendens, Cyperus microiria, Solanum nigrum, Galinsoga ciliata, Rorippa indica, Oryza sativa, Zea mays, Triticum aestivum, Glycine max, Gossypium herbaceum and Beta vulgaris were spot-wisely sown, and the soil was covered thereon in a thickness of about 1.5 cm. When the various weeds and crop plants grew to the 2 or 3 leaf stage, a herbicidal solution was uniformly sprayed on the foliages so that the active ingredient was applied in a predetermined concentration.

The herbicidal solution was prepared by diluting the wettable powder as described in the above Formulation Examples with water and applied onto the entire surface of the foliages of the weeds and the crop plants by a small spray. Four weeks after the application of the herbicide solution, the herbicidal effects against each weed and the phytotoxicities against each crop plant were determined on the basis of the standard ratings described in Test Example 1. The results are shown in Table 3. (Compound Nos. correspond to Compound Nos. in the Examples.)

TEST EXAMPLE 3 Test on the phytotoxicity against Triticum aestivum

A plastic box having a length of 15 cm, a width of 22 cm and a depth of 6 cm was filled with a sterilized diluvial soil, and seeds of Triticum aestivum, Avena fatua and Alopecurus myosuroides were spot-wisely sown, and the soil was covered thereon in a thickness of 1 cm.

When the plants grew to the 2 or 3 leaf stage, a herbicidal solution was uniformly sprayed on the foliages so that the active ingredient was applied in a predetermined concentration by a small spray. Twenty days after the treatment, the herbicidal effects against weeds and the phytotoxicity against Triticum aestivum were determined on the basis of the standard ratings described in Test Example 1. The results are shown in Table 4. (Compound Nos. correspond to Compound Nos. in the Examples.)

In Tables 2, 3 and 4, the following abbreviations are used.

Dose: Dose of active ingredient

EC: Echinochloa crus-galli (barnyardgrass)

DI: Digitaria adscendens (large crabgrass)

CY: Cyperus microiria (annual sedge)

SO: Solanum nigrum (black nightshade)

GA: Galinsoga ciliata (hairy galinsoga)

RO: Rorippa indica (fieldcress)

OR: Oryza sativa (rice)

ZE: Zea mays (corn)

TR: Triticum aestivum (wheat)

GL: Glycine max (soybean)

GO: Gossypium herbaceum (cotton)

BE: Beta vulgaris (sugar beet)

AV: Avena fatua (wild oat)

AL: Alopecurus myosuroides (blackgrass)

                                      TABLE 2                                      __________________________________________________________________________     Comp. No.                                                                             Dose kg/ha                                                                           EC DI CY SO GA RO OR ZE TR GL GO                                  __________________________________________________________________________     1      0.16  3  4  2  5  5  5  5  1  2  1  1                                          0.32  4  5  4  5  5  5  5  2  3  2  3                                          0.63  5  5  5  5  5  5  5  3  4  3  4                                   3      0.16  2  3  3  4  5  5  3  0  0  1  2                                          0.32  3  4  4  5  5  5  4  0  1  2  3                                          0.63  4  5  5  5  5  5  5  0  2  4  4                                   4      0.63  3  4  3  5  5  5  4  0  2  1  1                                   5      0.63  4  5  3  4  5  5  5  1  0  1  2                                   7      0.16  1  2  1  5  5  5  4  0  0  0  0                                          0.32  2  3  2  5  5  5  5  0  0  0  1                                          0.63  3  4  4  5  5  5  5  1  1  1  2                                   8      0.63  3  5  4  5  5  5  4  1  0  2  1                                   13     0.16  1  1  2  5  5  5  2  0  0  0  1                                          0.32  2  2  3  5  5  5  3  0  1  1  2                                          0.63  3  4  4  5  5  5  4  0  2  2  3                                   19     0.63  3  2  3  5  5  5  0  0  0  1  1                                   20     0.63  2  1  1  4  5  5  0  2  1  2  1                                   21     0.63  2  1  1  5  5  5  4  1  3  3  3                                   28     1.6   3  4  4  4  5  5  4  1  1  2  2                                          3.2   4  5  5  5  5  5  5  2  2  3  3                                          6.3   5  5  5  5  5  5  5  3  3  4  4                                   Comparative                                                                           2.5   0  0  0  0  0  0  0  0  0  0  0                                   Compound A                                                                     Comparative                                                                           2.5   0  0  0  0  0  0  0  0  0  0  0                                   Compound B                                                                     __________________________________________________________________________      Comparative Compounds A and B:                                                 Disclosed in Japanese Unexamined Patent Publication No. 122671/1988            ##STR46##                                                                

                                      TABLE 3                                      __________________________________________________________________________     Comp. No.                                                                             Dose kg/ha                                                                           EC DI CY SO GA RO OR ZE TR GL GO BE                               __________________________________________________________________________     1      0.16  4  4  1  5  5  5  4  2  1  4  4  5                                       0.32  5  5  2  5  5  5  5  3  1  5  5  5                                       0.63  5  5  3  5  5  5  5  4  2  5  5  5                                3      0.16  5  4  5  5  5  5  1  0  0  4  4  4                                       0.32  5  5  5  5  5  5  2  0  1  5  5  5                                       0.63  5  5  5  5  5  5  3  1  2  5  5  5                                4      0.63  5  3  2  5  5  5  2  1  1  4  4  5                                5      0.16  4  2  1  5  5  5  3  0  0  4  2  4                                       0.32  5  3  1  5  5  5  3  1  0  5  3  5                                       0.63  5  4  2  5  5  5  4  2  0  5  4  5                                7      0.16  1  1  1  5  5  5  4  1  0  1  4  3                                       0.32  2  2  2  5  5  5  5  2  1  2  5  4                                       0.63  3  3  3  5  5  5  5  2  1  3  5  5                                8      0.16  4  1  1  5  5  5  3  1  0  4  2  3                                       0.32  5  2  2  5  5  5  4  1  0  5  3  4                                       0.63  5  4  3  5  5  5  4  3  1  5  4  5                                10     0.63  1  2  1  5  5  5  0  0  0  5  3  5                                13     0.16  3  2  1  5  5  5  2  0  1  5  2  3                                       0.32  4  3  2  5  5  5  3  1  2  5  3  4                                       0.63  5  4  3  5  5  5  4  2  3  5  4  5                                15     0.63  2  1  1  5  5  5  0  1  1  4  3  4                                18     0.63  2  1  1  5  5  5  0  1  0  4  2  3                                19     0.16  2  1  1  5  5  5  0  0  0  4  4  3                                       0.32  3  2  2  5  5  5  0  1  1  5  5  4                                       0.63  4  4  3  5  5  5  1  2  2  5  5  5                                20     0.16  1  0  0  4  5  5  0  0  0  4  2  2                                       0.32  2  1  1  5  5  5  1  0  1  5  3  3                                       0.63  3  2  2  5  5  5  2  1  2  5  4  4                                21     0.16  0  0  0  4  5  5  0  0  0  4  3  4                                       0.32  1  1  0  5  5  5  1  0  1  5  4  5                                       0.63  2  2  1  5  5  5  2  0  2  5  5  5                                22     0.63  2  1  1  5  5  5  2  1  2  4  3  3                                28     1.6   3  3  1  5  5  5  1  0  0  4  4  4                                       3.2   4  4  2  5  5  5  2  1  1  5  5  5                                       6.3   5  5  2  5  5  5  3  2  2  5  5  5                                Comparative                                                                           2.5   0  0  0  0  2  0  0  0  0  0  0  0                                Compound A                                                                     Comparative                                                                           2.5   0  0  0  0  1  0  0  0  0  0  0  0                                Compound B                                                                     __________________________________________________________________________      Comparative Compounds A and B:                                                 Disclosed in Japanese Unexamined Patent Publication No. 122671/1988.           ##STR47##                                                                

                  TABLE 4                                                          ______________________________________                                         No.          g/a    TR         AV   AL                                         ______________________________________                                          3           0.4    0          4    4                                                       0.8    0          5    5                                                       1.6    0          5    5                                          19           0.4    0          3    3                                                       0.8    0          4    4                                                       1.6    0          5    5                                          21           0.4    0          3    3                                                       0.8    0          4    4                                                       1.6    0          5    5                                          Reference*   0.4    0          0    0                                          Compound     0.8    0          1    1                                                       1.6    0          2    2                                          ______________________________________                                          *Diclofop-methyl                                                               ##STR48##                                                                 

We claim:
 1. A pyridinesulfonamide derivative of the formula (I) and a salt thereof:wherein R¹ is a halogen atom, a trifluoromethyl group, a C₁ -C₆ alkoxycarbonyl group, a C₁ -C₆ mono- or di-alkylaminocarbonyl group, a C₁ -C₆ alkoxy group, a C₁ -C₆ alkylsulfonyl group, a C₁ -C₆ alkylthio group, a C₁ -C₆ alkyl group substituted by a C₁ -C₆ alkoxy group, a C₁ -C₆ alkyl group substituted by a C₁ -C₆ mono- or poly-halogenoalkoxy group, a C₁ -C₆ mono- or poly-halogenoalkoxy group, a C₁ -C₆ mono- or di-alkylaminosulfonyl group, a C₁ -C₆ alkoxyaminosulfonyl group substituted by a C₁ -C₆ alkyl group, a nitro group, a C₁ -C₆ alkyl group substituted by a C₁ -C₆ alkylthio a C₁ -C₆ alkyl group Substituted by a C₁ -C₆ group, a C₁ -C₆ alkyl group substituted by a C₁ - C₆ alkylsulfonyl group, or a C₁ -C₆ alkyl group substituted by a C₁ -C₆ alkoxycarbonyl group; R² is a hydrogen atom or a halogen atom; X is a oxygen atom or a sulfur atom; and ##STR49## wherein each of a, b, c and d independently represents a hydrogen atom, a C₁ -C₆ alkyl group, a C₂ -C₆ alkenyl group, a C₂ -C₆ alkynyl group, a C₁ -C₆ alkyl group mono- or poly-substituted by a halogen atom, a C₁ -C₆ alkoxy group, a C₁ -C₆ alkyl group substituted by a C₁ -C₆ alkoxy group, a C₁ -C₆ alkoxycarbonyl group, a C₁ -C₆ alkyl group substituted by a C₁ -C₆ alkylthio group, a C₁ -C₆ alkyl group substituted by a C₁ -C₆ alkylsulfonyl group, a C₁ -C₆ alkylthio group, a C₁ -C₆ alkylcarbonyl group, a C₃ -C₇ cycloalkyl group, a C₃ -C₇ cycloalkenyl group, a cyano group, or a phenyl or benzyl group which may be mono- or poly-substituted by a halogen atom, a trifluoromethyl group, a C₁ -C₆ alkyl group, a C₁ -C₆ alkoxy group, a C₁ -C₆ alkoxycarbonyl group or a nitro group.
 2. The pyridinesulfonamide derivative of claim 1, which is ##STR50## wherein R¹ is a halogen group, a trifluoromethyl group or a dimethylaminocarbonyl group;a is a hydrogen atom or a methyl group; d is a hydrogen atom or a C₁ -C₃ alkyl group; e is a hydrogen atom, a halogen atom, a trifluoromethyl group or a methoxy group; n is 1 or
 2. 3. The pyridinesulfonamide derivative of claim 1, which is ##STR51##
 4. The pyridinesulfonamide derivative of claim 1, which is ##STR52##
 5. The pyridinesulfonamide derivative of claim 1, which is ##STR53##
 6. The pyridinesulfonamide derivative of claim 1, which is ##STR54##
 7. The pyridinesulfonamide derivative of claim 1, which is ##STR55##
 8. The pyridinesulfonamide derivative of claim 1, which is ##STR56##
 9. A selective herbicide containing an effective amount of the compound of claim 1 as an active ingredient, in admixture with a carrier.
 10. The selected herbicide of claim 9, wherein the compound is ##STR57## wherein R¹ is a halogen group, a trifluoromethyl group or a dimethylaminocarbonyl group;a is a hydrogen atom or a methyl group; d is a hydrogen atom or a C₁ -C₃ alkyl group; e is a hydrogen atom, a halogen atom, a trifluoromethyl group or a methoxy group; n is 1 or
 2. 11. The selective herbicide of claim 9, wherein the compound is ##STR58##
 12. The selective herbicide of claim 9, wherein the compound is ##STR59##
 13. The selective herbicide of claim 9, wherein the compound is ##STR60##
 14. The selective herbicide of claim 9, wherein the compound is ##STR61##
 15. The selective herbicide of claim 9, wherein the compound is ##STR62##
 16. The selective herbicide of claim 9, wherein the compound is ##STR63##
 17. A method of treating crop plants which comprises administering a herbicidally effective amount of the compound of claim 1 as an active ingredient.
 18. The method of claim 17, wherein the compound is ##STR64## wherein R¹ is a halogen group, a trifluoromethyl group or a dimethylaminocarbonyl group;a is a hydrogen atom or a methyl group; d is a hydrogen atom or a C₁ -C₃ alkyl group; e is a hydrogen atom, a halogen atom, a trifluoromethyl group or a methoxy group; n is 1 or
 2. 19. The method of claim 17, wherein the compound is ##STR65##
 20. The method of claim 17, wherein the compound is ##STR66##
 21. The method of claim 17, wherein the compound is ##STR67##
 22. The method of claim 17, wherein the compound is ##STR68##
 23. The method of claim 17, wherein the compound is ##STR69##
 24. The method of claim 17, wherein the compound is ##STR70## 